A snowmobile having a steering ski and an endless drive track according to the prior art is equipped with a steering mechanism of the type in which the steering ski is supported through a leaf spring so that the ski and spring may be turned together clockwise and counter-clockwise. The conventional steering mechanism using the leaf spring has a disadvantage that the steering ski has its transverse rigidity so deteriorated that it is liable to experience a transversely falling phenomenon, when it is abruptly turned.
With this in mind, the present invention contemplates a steering mechanism in which a steering ski is mounted to the lower end of a supporting member which in turn is mounted to the chassis of a snowmobile in a manner to move up and down so that the supporting member is biased to return downward, and so that the steering ski and the supporting member are turned together clockwise and counter-clockwise. For example, there is disclosed a strut type suspension system, in which a strut is received in an outer cylinder fixed to the chassis so that it extends through the outer cylinder while being rotatable and movable up and down, in which the steering ski is mounted to the strut, and in which the strut is supported elastically by means of a suspension spring. In this invention, the upper end of the strut is supported rotatably with respect to the chassis so that the steering operation is performed by integrally turning the strut and the steering ski.
Therefore, in a suspension system having a supporting member such as a strut rotatable together with a steering ski, the rotations take place not only at the sliding portion for receiving the supporting member in a manner to rotate and move up and down, but also between the leaf spring and the chassis whereby to increase the frictional resistance due to the rotations so that an accordingly increased force is required for operating the steering handle with the resultant disadvantage that the handling becomes heavy.